Visibility Matters is a monthly column by AfterEllen.com Founder Sarah Warn about larger trends affecting lesbian/bi women in entertainment and the media.

This weekend at the annual Women’s Event fundraiser for New York’s gay and lesbian center, L Word creator Ilene Chaiken said that when she launched her series six years ago, she assumed there would be plenty of other shows with prominent lesbian leads on mainstream TV by the time it ended.

But The L Word‘s final season begins in a few months, and not only are there no lesbian cop shows, comedies, or medical dramas on broadcast TV, there are no lesbian characters, period. At least, not on primetime broadcast television, home to America’s most-watched shows.

At the turn of the century, there were several lesbian series regulars on primetime broadcast TV. In the 2004-2005 season, there were four or five. By 2006-2007, it was down to one.

This season (2008-2009), the number of lesbians among the 616 series regulars is approximately zero.

(There are only four lesbians in the recurring characters category — the rarely seen gay mayor on Friday Night Lights, and three cartoon lesbians).

The L Word’s Shane and Alice wonder where all the lesbians on broadcast TV have gone

To be fair, we did have one lesbian series regular on a primetime broadcast series this season — for two weeks

I’m referring, of course, to Grey’s Anatomy‘s Dr. Erica Hahn (Brooke Smith), who finally came out as a lesbian last week, and was promptly fired from the show by ABC execs. Smith’s last episode of Grey’s is tonight, and when she leaves, the only lesbian couple on primetime broadcast TV goes with her.

Dr. Erica Hahn on Grey’s Anatomy

But the controversial departure of Erica Hahn is just the latest casualty of long, slow decline of lesbian characters on primetime broadcast television.

Despite the gain in lesbian visibility in pop culture due to the popularity of high-profile lesbians like Ellen DeGeneres, Melissa Etheridge, Rosie O’Donnell, and Rachel Maddow, lesbians characters have dwindled down to near extinction on scripted television. (And when South of Nowhere ends next month, and The L Word two months after that, lesbians will be close to invisible on cable programming, as well, save for shows on LGBT channels like Logo and Here TV, which still aren’t accessible to many Americans).

And despite the fact that we’ve been writing about this trend for years now, this near-invisibility of lesbian characters on scripted primetime broadcast TV has generally been ignored by just about everyone but us.

GLAAD noted the lack of scripted lesbians in their most recent annual report about LGBT characters, but this statistic was overshadowed by the larger one showing that the total number of LGBT characters on television overall has almost doubled — which was the statistic touted in the headline by almost every news outlet covering the report.

Almost none of the mainstream news coverage of Brooke Smith’s departure from Grey‘s this week has mentioned that her character is the only lesbian character, in the only lesbian relationship, on primetime broadcast TV.